For (x-)blockdev-create, all protocol drivers that support image
creation also need to offer a .bdrv_truncate() implementation that
matches in features. A previous series of mine brought gluster's and
sheepdog's implementation up to par regarding preallocated truncation;
but I forgot about drivers that have a .bdrv_create() but no
.bdrv_truncate() at all.
There is only one of these, and that is ssh. Since libssh2 does not
seem to know any way of truncating files, we can only support growing
files -- but that is what we need for (x-)blockdev-create.
Note that there are also drivers which do not support growing files,
namely iscsi and file-posix for host devices (maybe more? I hope not).
But these also pretty much ignore the specified size on .bdrv_create()
and just use the size of the existing device. They just check that the
specified size does not exceed the actual size, so that pretty much
matches what their .bdrv_truncate() supports, and we should be fine
Max Reitz (3):
block/ssh: Pull ssh_grow_file() from ssh_create()
block/ssh: Make ssh_grow_file() blocking
block/ssh: Add basic .bdrv_truncate()
block/ssh.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 53 insertions(+), 8 deletions(-)